2 Answers
2

The longer your beer takes to begin fermentation, the longer it is prone to (more easily) become infected.

Depending on how slowly it is being cooled, you may have clarity issues. You need to chill it quickly to form a good cold-break which is essential to clarity.

That said, 8 hours isn't a terrible amount of time for wort to sit. I've been in the same circumstance you described, even to the point where I've dozed off (aka drank too much while waiting until 4AM) and pitched the yeast as soon as I woke up, realizing I let my wort sit unattended. Make sure it's covered as best as possible (not the easiest to do with immersion chillers), not in a drafty area, and you will likely be fine.

Thanks for the explanation, that all makes a lot of sense. I was just assuming if ale yeast didnt like it hot, likely wild yeast wouldnt either... obviously wasnt thinking clearly. :) cheers
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Ugly DudeJan 14 '14 at 21:58

One drawback is that if bacteria or wild yeast does make it into your wort, it will have a head start on growth, where otherwise the inoculation of brewer's yeast might overpower the bad bugs and minimize impact.

Also, if you're not doing anything to expedite the chilling process, it may affect the isomerization of hops, depending on the style you're making. Basically, late addition hops flavor and aroma will change (generally in an undesirable way) if they stay in hot wort too long. No-chill brewing incorporates some practices (like first wort hopping) to counter this.